1. Field of the Invention
The invention relates to a heat transfer measurement device, in particular a flow monitor for the electrical measurement of heat losses in a flowing medium, with a preferably metallic, circular cylindrical measurement device housing having an outside thread, with a first temperature measurement element, with at least one heating element and a second temperature measurement element.
2. The Prior Art
Heat transfer measurement devices of the type discussed, i.e., in particular calorimetrically operating flow monitors, have been known for some time and in many different embodiments (see, for example, German Laid-open Patent Applications DE-OS Nos. 24 47 617, 26 29 051, 32 13 902 and 32 22 046). By means of these heat transfer measuring devices, hereinafter always designated as flow monitors, the temperature difference is measured. The first temperature measurement element measures a temperature determined by the heating element and the flowing medium, hereinafter called measurement temperature, while the second temperature measurement element measures a temperature, if possible not determined at all or determined in another way, by the heating element and by the flowing medium, hereinafter called reference temperature. Thus the first temperature measurement element, the heating element and the second temperature measurement element--as well as an evaluation circuit of no further interest here--are required for the operation of the flow monitors herein discussed.
If the medium the flow of which is to be monitored is a gas, the operationally required components--first temperature measurement element, heating element and second temperature measurement element--can be introduced into the gas flow more or less unprotected. However, if the flow of a liquid medium is to be monitored, the components required for operation--first temperature measurement element, heating element and second temperature measurement element--cannot be simply introduced into the liquid medium flow and it is necessary to dispose these components while protected inside a measurement device housing.
In a flow monitor of the type described above and already realized in actual use (see German Laid-open Application DE-OS No. 32 13 902), the measurement device housing is constructed in an offset manner. The first temperature measurement element and the heating element are located in the thinner part of the measurement device housing, while the second temperature measurement element is located in the thicker part of the measurement device housing in the end oriented towards the thinner part. The first temperature measurement element and the heating element are disposed in an aluminum disc. The aluminum disc provides the thermal connection between the front face of the measuring device housing and the first temperature measurement element on the one side and the heating element on the other side. The first temperature measurement element, the heating element and the aluminum disc are cast in an epoxy resin which is a good thermal conductor. The second temperature measurement element is located at a distance of approximately 1 cm from the front face of the measurement device housing and is also cast in an epoxy resin which is a good thermal conductor. Since the heat of the heating element is not intended to reach the second temperature measurement element, material which is a good thermal insulator is placed between the area which the first temperature measurement element and the heating element are disposed and the area where the second temperature measurement element is disposed.